Recycling of waste carpets has always been a problem confronting governments and environmental protection agencies worldwide, and the problem of recycling waste carpets lies mainly in separating fiber from backing adhesive, which typically is a mixture of CaCO3 and styrene-butadiene rubber (hereinafter SBR).
A carpet is usually composed of the fiber on a polypropylene (hereinafter PP) woven framework, a PP mesh on the bottom layer, and a mixture of CaCO3 and SBR in the middle. The mixture of CaCO3 and SBR are entirely adhered to the U-shaped root of the fiber. This brings about great difficulty in the recovery of useful fiber of the carpet.
Many companies have conducted a great deal of research in this respect, but no satisfactory solutions have been found so far. One example is disclosed in a patent application titled “Process for Recovery of Caprolactam from Waste Containing Nylon” filed in China in 1996 by DSM N. V. of Netherlands and published by the Chinese Patent Gazettes with a publication number of CN1196048. It solves the problem of recovering caprolactam from the waste containing nylon mainly by a chemical depolymerizing method. This method demands a large amount of investment and produces however no significant economic return.
In the prior art, there are mainly two methods for separating carpet fiber from the mixture of CaCO3 and SBR. One is dissolving SBR with a chemical solvent after shredding the carpet and then washing CaCO3 off by water. However, this method may severely pollute the environment and thus has not be widely accepted. The other method is shearing the fiber from the carpet with wool shears, but this method is low in both processing efficiency and recovery rate, and the output thereof is very poor.